The applicant proposed to provide buffers below, and on sides of a travel route of overhead traveling vehicles (see Japanese Laid-Open Patent Publication No. 2005-206371). In this manner, it is possible to reduce the number of stockers for storing articles, and buffers near a port at the transportation destination become available. Thus, for example, an article is transported to a buffer near the port at the transportation destination beforehand, and when the port becomes empty, the article is transported into the empty port. Further, by using the additional buffers, it is possible to divide transportation operation to be shared by a plurality of overhead traveling vehicles.
However, the buffers may obstruct operation of transporting equipment such as processing equipment into, or out of a position around the buffers. The buffers below the route are provided at positions lower than the overhead traveling vehicles for avoiding interference with the articles being transported by the overhead traveling vehicles. Further, the height of the buffers provided on the sides of the route is substantially the same as the height of the articles being transported by the overhead traveling vehicles. At the time of replacing the equipment, the overhead traveling vehicles automatically move to suitable positions for not obstructing the replacement operation. However, the buffers occupy positions above the paths or positions above equipment, and thus, obstruct movement of the equipment.